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Incidence

The frequency of this disorder is rare, with approximately 200 children reported worldwide, and males are affected nearly twice as often as females (ratio is 1.7 to 1). It is important to notice that autism is much more common than Landau-Kleffner syndrome. The cause of Landau-Kleffner syndrome is not known. It is not clear whether it is an inherited disorder or not, though pairs of siblings with the disorder have been described which lends evidence to a genetic association.

Clinical Characteristics

Landau-Kleffner Syndrome (LKS) is a rare form of childhood epilepsy that affects the parts of the brain that control speech and comprehension, causing severe language problems. The syndrome results in aphasia, which is the loss of the ability to comprehend and use words. This disorder is difficult to diagnose and may be confused with a variety of other conditions, including but not limited to mental retardation, autism, and learning disability problems. It is considered an epileptic syndrome. Children with Landau-Kleffner syndrome may experience the following symptoms: Trouble understanding words for no apparent reason. This may occur suddenly or gradually worsen over time. When this occurs, the parent often thinks the child is developing a hearing problem. Seizures are experienced in 70-85% of patients with this disorder (usually at night). However, in about 1/3 of these patients, only a single seizure is recorded. Behavioral problems may occur, including hyperactivity, decreased attention span, aggression, anger or rage, and oppositional behavior. Depression may also occur. The aphasia may develop suddenly or gradually, and people with this condition also have an abnormal electro-encephalogram (EEG). Children most often have problems with receptive language (understanding language spoken to them), and since these issues occur during a critical period of language development, they may have word production (finding and using words) problems that match or exceed their language comprehension problems. Children may begin showing signs of LKS anywhere from 18 months to 13 years of age. The beginning of aphasia symptoms usually occurs between the ages of 4 and 7 years, with language deterioration taking place over weeks to months or rapidly following a seizure episode. When this condition presents at birth, the age of onset of symptoms cannot be determined due to the fact that language problems are not recognized during the first 18 months of life. As mentioned previously, these early cases may be confused with a developmental language disorder, autism, attention deficit disorder, mental retardation, childhood schizophrenia, or emotional and behavioral problems.

Precipitants

None

Provocation Tests

None

Diagnostic Procedures

The child should be examined for language, speech and behavioral problems. There are guidelines for the number of words a child should speak per age and when children begin to use simple phrases and sentences, and when parts of speech and grammar are expected. Because language development is dependent on ability to hear, several tests can be used. Brainstem auditory evoked potentials and hearing tests (signals made in the brain when one hears a sound) can be performed to determine if the child can receive language sounds in the brain. Problems with the ears (ear infections, malformations, wax build up) can lead to hearing loss, a much more common cause of language problems in children. Imaging tests, such as an MRI, are performed in children with Landau-Kleffner to eliminate the possibility of conditions such as a brain tumor, demyelination, neurodegenerative disease, or central nervous system infections. An EEG will show the seizures, though an extended period of monitoring may be needed for the seizure to be detectable on the EEG.